Welsh capital (7)
I believe the answer is:
cardiff
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">welsh capital</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for cardiff that I've seen before include "Welsh capital" , "European capital, birthplace of Roald Dahl" , "Capital on the Taff" , "Welsh city" , "Capital of Wales" .)